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FieldSense Technology – Measure Voltages without Test Leads

Taking voltage and current measurements is not only be time-consuming but with live circuits also carries a potential safety risk. For a number of years, engineers have been using the Fluke T5 electrical tester with open-fork technology, allowing current measurements to be made without breaking the circuit, thus saving time and improving safety.

Image of a Fluke T6 taking measurement

Fluke engineers have now developed a new technology called FieldSense that also uses open fork method of non-contact measurement of up to 1000 V ac, which now means test leads are no longer needed for voltage measurement (provided unit is grounded – see how it works below).

How FieldSense works

Fluke uses the “open-fork” measurement method on the T5 to detect a magnetic field, which is used to derive an ac current, but for ac voltage measurements an electric field needs to be detected, which is where FieldSense was developed.

The way in which Fluke engineers solved this was to create a reference signal of known amplitude and frequency, which is grounded through capacitive coupling (path between contact point on tester, the operators hand and earth ground), so when the “open-fork” is placed over a live conductor, the ac electric field interacts (combines) with the reference signal and the resulting composite waveform is detected by an electronic sensor within the tester, which then after amplification, processing and digital calculations the voltage and frequency measurements are derived.Fluke_T6_FieldSense_5ef1eca20877048dccce349ce9290531abb15a58.jpg

When a capacitive path to ground is not available (like when an operator is wearing gloves, or on a ladder), then the black test probe can be connected to an earth point so a FieldSense measurement can be made.

Difference between voltage detection and FieldSense

There are many voltage detectors on the market like the pen style probe, which lights up when a voltage is present, but this is the limitation of a detector, it simply shows that a voltage is present, not what the voltage is. The advantage of using FieldSense technology is that an accurate ac voltage measurement can be made without making contact with a live conductor.

How to use FieldSense technology on the Fluke T6

The video below shows how easy it is to make an ac voltage measurement using the Fluke T6:

Common applications include:

  • Wire runs in conduit and junction boxes
  • Feed circuits coming into motors (up to 200A)
  • Distribution panels
  • HVAC equipment
  • Disconnects
  • Conduit cases (using the black test lead for grounding)

The benefits of using the Fluke T6 and FieldSense include:

  • Safer voltage measurements can be taken
  • Faster troubleshooting by measuring through the open fork around a conductor
  • Can measure voltage and current at the same time


Handheld Testers with FieldSense Technology

With a background in electronics and electrical engineering, with a keen eye on innovation and how things work.